1. Field of the Invention
The invention relates to an impact-resistant optical component, more particularly to a barrel assembly for a lens device that can resist an impact.
2. Description of the Related Art
As shown in FIG. 1, a conventional lens device includes a stationary barrel 11 surrounding an axis (L), a lens module 12 sleeved inside the stationary barrel 11 and having a set of lenses (not shown) and an outer surrounding surface 121, an outer lens barrel 13 sleeved outside the stationary barrel 11 and having an inner wall surface 131, and three angularly spaced apart coupling pins 14 (only two are shown).
The stationary barrel 11 has three angularly spaced apart guide slots 111 (only two are shown), each of which is parallel to the axis (L). The outer lens barrel 13 has three angularly spaced apart cam slots 132 (only two are shown) formed in the inner wall surface 131, each of which extends circumferentially. Each of the coupling pins 14 is connected to the outer surrounding surface 121 of the lens module 12, extends radially and outwardly toward the outer lens barrel 13, and has a connecting section 141 connected to the lens module 12, a guide section 142 extending from the connecting section 141 and through a respective one of the guide slots 111 so as to be guided thereby, and a retaining section 143 extending from the guide section 142 and retained slidably in a respective one of the cam slots 132.
When the outer lens barrel 13 rotates relative to the stationary barrel 11, it drives the coupling pins 14 to slide respectively along the cam slots 132. The coupling pins 14 are also guided respectively by the guide slots 111 in the stationary barrel 11 to move in directions parallel to the axis (L). Since the connecting section 141 of each of the coupling pins 14 is connected to the lens module 12, the lens module 12 will move together with the coupling pins 14, thereby resulting in zoom adjustment.
However, when an impact force (F) is applied to the lens module 12 (see FIG. 2), the retaining section 143 of a respective one of the coupling pins 14 may be forced to slide out of the respective one of the cam slots 132, resulting in the lens module 12 and the coupling pins 14 being stuck in the outer lens barrel 13.
As shown in FIGS. 3 and 4, another conventional lens device has a structure similar to that shown in FIG. 1. Unlike the lens device of FIG. 1, the lens device of FIG. 3 further includes three angularly spaced apart reinforcing pins 15 (only two are shown) and three reinforcing slots 133 formed in the inner wall surface 131 of the outer lens barrel 13 and extending parallel to the cam slots 132 in the inner wall surface 131, respectively. Each of the reinforcing pins 15 is connected to the outer surrounding surface 121 of the lens module 12, extends radially and outwardly toward the outer lens barrel 13, and has a connecting part 151 connected to the lens module 12, a guide part 152 extending from the connecting part 151 and through a respective one of the guide slots 111 so as to be guided thereby, and a retaining part 153 extending from the guide part 152 and retained slidably in a respective one of the reinforcing slots 153. The coupling pins 14 cooperate with the reinforcing pins 15 to bear the impact force (F), thereby distributing the impact force (F) and preventing the pins 14, 15 from sliding out of the slots 132, 133.
However, the requirement of forming the additional reinforcing slots 133 increases the lengths of the outer lens barrel 13 and the stationary barrel 11, thereby leading to a relatively thick lens device. Moreover, the disposition of the reinforcing pins 15 results in a higher manufacturing cost.